Modular glenoid prosthesis

ABSTRACT

A method of assembling a glenoid assembly. The method includes selecting a base from a plurality of bases. At least one of the plurality of bases has a size different than a size of one of the other of the plurality of bases. The selected base is coupled to an articulating member and the selected base is locked to the articulating member via a locking mechanism.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. patent application Ser. No. 12/953519 entitled “MODULAR GLENOID PROSTHESIS and cross reference is made to the following application U.S. patent application Ser. No. 12/953522 entitled “MODULAR GLENOID PROSTHESIS”, both of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a prosthetic glenoid component and particularly to a modular glenoid assembly for attachment to a glenoid surface of a scapula to replace a natural socket of a shoulder and to provide a bearing surface for a head portion of an arm bone or humerus.

BACKGROUND

During the lifetime of a patient, it may be necessary to perform a total shoulder replacement procedure on the patient as a result of, for example, disease or trauma. In a total shoulder replacement procedure, a humeral component having a head portion is utilized to replace the natural head portion of the arm bone or humerus. The humeral component typically has an elongated intramedullary stem which is utilized to secure the humeral component to the patient's humerus. In such a total shoulder replacement procedure, the natural glenoid surface of the scapula is resurfaced or otherwise replaced with a glenoid component which provides a bearing surface for the head portion of the humeral component.

Glenoid components have heretofore been designed which include a number of plastic inserts coupled to metal backings The metal backings are provided to secure the plastic inserts to the glenoid surface of the scapula. However, use of such two-piece glenoid components has a number of drawbacks associated therewith. For example, it is possible over the useful life of the glenoid component for the plastic inserts to separate from the metal backing thereby necessitating replacement of the glenoid component. In addition, over time wear of the plastic insert inherently occurs at the interface between plastic insert and the metal backing It is possible for the plastic insert to wear to a degree which necessitates replacement of the glenoid component. It should be appreciated that in either case, such replacement of the glenoid component requires the patient to again be subjected to a surgical procedure and the subsequent recovery period associated therewith.

In response to the shortcomings associated with two-piece glenoid component designs, a number of one-piece glenoid components have heretofore been designed. In regard to such one-piece designs, a body portion, having a bearing surface defined therein for receiving the head of the humeral component, has a number of attachment pegs integrally formed therewith. The attachment pegs are advanced and thereafter secured into a corresponding number of holes which are drilled in the glenoid surface of the scapula by use of bone cement. An example of such a one-piece glenoid component that is designed to be secured to the scapula by use of bone cement is disclosed in U.S. Pat. No. 5,032,132 issued to Matsen, III et al.

As with the two-piece designs, certain one-piece glenoid components which have heretofore been designed have a number of drawbacks associated therewith. For example, some studies have speculated that it may be desirable to secure artificial components to natural bone structures without the use of bone cement. Glenoid components which have been designed to be secured to the scapula by the use of bone cement generally cannot be secured to the natural glenoid without use of the same.

Many glenoid component designs have been manufactured to address different types of scapular deficiencies. For example, some glenoid components have anchor pegs with flexible fins that are designed to act as barbs when inserted into the scapula. Other designs may utilize glenoid components with a buttress extending from the glenoid to fill larger defects in the natural glenoid. These may also include anchor and/or stabilizing pegs. In other embodiments a vault-filling glenoid may be used to fill a natural glenoid that has severe defects.

However, one problem with even existing modular designs, is that they do not provide the surgeon with the option of using different designs once surgery has started. Also, if a kit was to include all the different sizes and variations, the kit would be quite large and cumbersome to bring into surgery.

Another problem is that glenoid bone quality and surface deterioration varies significantly from patient-to-patient. Therefore, in current designs, having standard peg or buttress or vault locations may not work with specific patients' anatomy. Furthermore, in some embodiments, the surgeon may choose a medial-lateral approach. In that approach, it may be difficult to fit posts and vaults that are designed to be inserted from an overhead position.

SUMMARY

According to one embodiment of the present invention, a kit for making glenoid prosthesis is provided. The kit includes an articulating member having an articulation side and an opposing second side opposing the articulating member. The opposing second side includes a locking mechanism. The kit further includes a plurality of bases. Each of the plurality of bases has an articulating-member facing side and a glenoid attachment side. Each of the plurality of glenoid attachment sides includes at least one glenoid attachment member extending outwardly and is sized and shaped to extend into a patient's glenoid. The glenoid attachment member of one of the plurality of bases differs from the glenoid attachment member of at least one other of the plurality of bases. Each of the plurality of bases includes a locking mechanism sized and shaped to lock each of the plurality of bases to the articulating member.

According to another embodiment of the present invention, the method of assembling a glenoid assembly is provided. A base is selected from a plurality of bases. At least one of the plurality of bases has a size different than a size of one of the other of the plurality of bases. The selected base is coupled to an articulating member. The selected base is locked to the articulating member via a locking mechanism.

According to yet another embodiment of the present invention, a kit for making glenoid prosthesis is provided. The kit includes an articulating member having an articulation side and an opposing second side opposing the articulating member. The opposing second side includes a locking mechanism. The kit further includes a plurality of bases, and each of the plurality of bases has an articulating-member facing side and a glenoid attachment side. Each of the plurality of glenoid attachment sides differs from the glenoid attachment side of at least one other of the plurality of bases. Each of the plurality of bases includes a locking mechanism sized and shaped to lock each of the plurality of bases to the articulating member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a glenoid assembly according to one embodiment of the present invention.

FIG. 2 is a perspective view of a base of the glenoid assembly of FIG. 1.

FIG. 3 is a perspective view of an articulating member of the glenoid assembly of FIG. 1.

FIG. 4 is a perspective view of the modular glenoid assembly of FIG. 1 positioned between a glenoid surface of a scapula and a humeral component.

FIG. 5 is a perspective view of a glenoid assembly according to another embodiment of the present invention.

FIG. 6 is an illustration showing a kit for making a modular glenoid assembly according to one embodiment of the present invention.

FIG. 7 is an illustration of a base of the glenoid assembly according to another embodiment of the present invention.

FIG. 8 is a flow chart illustrating a method for assembling the modular glenoid assembly according to one embodiment of the present invention.

Additional features of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.

DETAILED DESCRIPTION OF THE DRAWINGS

A modular glenoid assembly 10 is provided in accordance with the present invention. FIG. 1 shows glenoid assembly 10 including a base 12 and an articulation member 14. The base 12 and articulation member 14 are locked in a fixed relationship. As shown in FIGS. 1 and 2, the base 12 includes a first side 16 and a second side 18. The first side 16 includes a finned anchor peg 20 and a cemented peg 22 sized and shaped to attach to a glenoid as will be described further below. Although in this embodiment the base 12 includes a single finned anchor peg 20 and a single cemented peg 22, it should be understood that in other embodiments, there may be differing numbers of pegs 20, 22. Furthermore, the base 12 may include other types of attachment members such as pins, screws, wedge-shaped fillers, spikes. The second side 18 of the base 12 is generally flat and is sized and shaped to abut the articulation member 14.

The base 12 also includes locking features 24. The locking features 24 in the embodiment illustrated in FIGS. 1 and 2 include a locking recess 26 and a pair of locking protrusions 28. These will be described below in further detail.

Turning now to FIGS. 1 and 3, the articulation member 14 will be further described. The articulation member 14 includes an articulation side 30 and an attachment side 32. The attachment side 32 is sized and shaped to receive the second side 18 of the base 12. The attachment side 32 includes an opening 34 defined on three sides by walls 36 of the attachment side 32. The fourth side is open, to allow the base 12 to slide into the articulating member 14. The top of the three walls 36 may include a lip 38 that extends out into the recess 34. The lip 38 exerts pressure against the base 12 and keeps the base from falling out of the articulating member 14.

The articulating member 14 further includes locking features 40 sized and shaped to engage the locking features 24 of the base 12. As shown in this embodiment, the locking features 40 include a pair of wall recesses 42. The pair of wall recesses 42 engages the pair of locking protrusions 28 of the base 12 (FIG. 2) so as to lock the base 12 to the articulating member 14. As the base 12 is slid in through the open side 38, the locking protrusions 28 will snap lock into place in the recesses 42. In this embodiment, the locking features 24 of the base 12 also includes the locking recess 26 that corresponds to a projection 44 in the articulating member 14. The projection 44 extends out into the recess 34 of the articulation member 14 and engages the locking recess 26 in a snap-locked configuration. Other types of locking arrangements such as tapers, locking rings, and other known locking mechanisms may be used.

Turning now to FIG. 4, the glenoid assembly 10 is shown with respect to a humerus 46 and a scapula 48. Glenoid assembly 10 is designed to be attached to glenoid surface 49 of scapula 48 to replace the natural glenoid surface. As shown, the finned anchor peg 20 and cemented peg 22 correspond to holes 50 drilled into the glenoid surface 49. The finned anchor peg 20 and cemented peg 22 will be placed in the holes 50, locking the glenoid assembly 10 to the glenoid surface 49.

The articulation side 30 of the articulation member 14 is smooth and will articulate with the head portion 52 of the humeral component 46. In some embodiments, the head portion 52 may also be an implant. In other embodiments, the head portion 52 may be the natural humeral head.

FIG. 4 illustrates an embodiment in which the glenoid assembly 10 is assembled prior to the glenoid assembly 10 being implanted into the prepared glenoid 49. However, in other embodiments, the prepared glenoid 49 may be prepared as described above. Then, the base 12 is inserted into the holes 50 of the prepared glenoid 49. The opening 34 of the articulating member 14 is then slid onto the base 12, locking the base 12 and the articulating member 14.

Turning now to FIG. 5, another embodiment of the present invention is illustrated. In this embodiment, a glenoid assembly 60 includes a base 62 and an articulating member 64. A modular glenoid assembly 60 is provided in accordance with the present invention. FIG. 5 shows glenoid assembly 60 including a base 62 and an articulation member 64. The base 62 and articulation member 64 are locked in a fixed relationship. As shown in FIG. 5, the base 62 includes a first side 66 and a second side 68. The first side 66 includes a wedge-shaped filler 70 sized and shaped to attach to a glenoid. Similar to how was described in the previous embodiment, a glenoid is prepared to fit the wedge-shaped filler 70. Although in this embodiment the base 62 includes a wedge-shaped filler 70, it should be understood that in other embodiments, there may be other attachment-type mechanisms, such as cemented pegs, finned anchor pegs, pins, screws, and/or spikes. The second side 68 of the base 62 is generally flat and is sized and shaped to abut the articulation member 14.

The base 62 also includes locking features 72. The locking features 72 in the embodiment illustrated in FIG. 5 include a recess 73 defined by the wedge-shaped filler 70 and a lip 74 that extends outwardly. The recess 73 and lip 74 will be described further below.

Turning now to the articulation member 64, the articulation member 64 includes an articulation side 76 and an attachment side 78. The attachment side 78 is sized and shaped to receive the second side 68 of the base 62. The attachment side 78 includes an opening 80 defined on two sides by walls 82 of the attachment side 78. The other two sides 84 oppose one another and are open, to allow the base 62 to slide into the articulating member 64. The top of the two walls 82 may include a projection 86 that extends out into the recess 73. The projection 86 exerts pressure against the base 62 and keeps the base from falling out of the articulating member 64. In use, the base 62 is slid into one of the open sides 84 and the lip 74 engages the side walls 82, while the projection 86 fits within the recess 73 of the base 62. In some embodiments, there may be three side walls 82, not just two and only one open side 84. Also, other types of locking arrangements such as tapers, locking rings, and other known locking mechanisms may be used.

Turning now to FIG. 6, a kit 100 for modular glenoid prosthesis is shown. The kit includes an articulating member 102 and a plurality of bases 104. The articulating member 102 includes an articulating side 106 and an opposing second side 108. The opposing second side includes a locking mechanism 110. In this embodiment, the locking mechanism 110 is the same as that described in FIGS. 1-4. In other embodiments, the locking mechanism 110 may be of the same type as described in FIG. 5.

The plurality of bases 104 includes a pegged base 112 and a wedge-shaped filler base 114. Each of the plurality of bases 104 have an articulating-member facing side 116 and a glenoid attachment side 118, which includes at least one glenoid attachment member 120 extending outwardly and sized and shaped to extend into a patient's glenoid. The pegged base 112 has a glenoid attachment member 120 that includes a finned anchor peg 122 and a cemented peg 124. The wedge-shaped filler base 114 includes a glenoid attachment member 120 that is a wedge-shaped filler 126. Other glenoid attachment members 120 may also be included, such as screws, pins, spikes, and other numbers of pegs 122, 124. Each of the plurality of bases 104 also includes a locking mechanism 128. The locking mechanism 128 is of the type described in FIGS. 1-4. In other embodiments, the locking mechanism may be of the same type as described with respect to FIG. 5.

Turning now to FIG. 7, another embodiment of the present invention will be shown. In this embodiment, a modular base 130 is included. The modular base 130 includes a support base 132 and a plurality of glenoid attachment members 133. The support base 132 includes attachment mechanisms 134. In this case, the attachment mechanisms 134 are generally spherical recesses. The glenoid attachment members 133 also include attachment mechanisms 136. In this embodiment, the attachment mechanisms are generally spherical shaped balls that lock into the recesses on the support base 132. Other types of attachment mechanisms may be used. Also, any number and type of glenoid attachment members 133 may be included, such as wedge-shaped fillers, screws, pins, spikes, and other numbers and types of pegs. The base 130 will lock into an articulating member 14, 64, 102 as described above in reference to FIGS. 1-6.

All of the pieces described above may be made of polyethylene, such as ultrahigh molecular weight polyethylene. Other biocompatible plastics may also be used. In some embodiments, biocompatible metals may also be used. In other embodiments, some of the parts, such as the articulation member may be made of biocompatible metal while other parts, such as the base may be made of biocompatible plastics. In other words, any combination of biocompatible plastics and/or metals may be used.

Turning now to FIG. 8, a method for using a modular glenoid according to one embodiment of the present invention will be described. First, at step s200, a base is selected from a plurality of bases. Then, at step s202, the selected base is inserted into the prepared glenoid. An articulating member is then slid into the base, locking the articulating member to the base (step s204). 

The invention claimed is:
 1. The method of assembling a glenoid assembly, the method comprising: selecting a base from a plurality of bases, wherein at least one of the plurality of bases has a size different than a size of one of the other of the plurality of bases, each of the plurality of bases having an articulating-member facing side and a glenoid attachment side, wherein each of the plurality of glenoid attachment sides include at least one glenoid attachment member extending outwardly and sized and shaped to extend into a patient's glenoid, wherein the glenoid attachment member of one of the plurality of bases differs from the glenoid attachment member of at least one other of the plurality of bases, and wherein each of the plurality of bases includes a locking mechanism sized and shaped to lock each of the plurality of bases to the articulating member, wherein the plurality of bases includes at least one finned peg and one wedge-shaped filler; coupling the selected base to an articulating member; and locking the selected base to the articulating member via a locking mechanism.
 2. The method of claim 1, wherein the locking mechanism includes a lip on one of the selected base and the articulating member and a recess on the other of the selected base and the articulating member.
 3. The method of claim 1, wherein the locking mechanism includes a pair of protrusions on one of the selected base and the articulating member and a pair of recesses on the other of the selected base and the articulating member.
 4. The method of claim 1, further comprising inserting the selected base into a prepared glenoid.
 5. The method of claim 4, wherein the inserting the selected base into the prepared glenoid is performed before the selected base is coupled to the articulating member. 